The studies in this application focus on the use of rhythmic sensory stimuli to improve motor performance in chronic motor dysfunction conditions. Two population groups characterized by progressive loss in the ability to coordinate complex movements will be examined: (1) idiopathic Parkinson's Disease patients of 3-5 years duration with decreased responsiveness to L-Dopa therapy and (2) healthy elderly subjects. Specific aims will (1) compare the effectiveness of auditory versus visual stimuli in facilitating movement sequencing, (2) identify motor tasks most responsive to sensory cueing and (3) establish a framework for the future development of effective rehabilitative techniques using rhythmic sensory cueing to improve motor performance in a variety of motor dysfunction conditions. These studies will also provide valuable insights into the mechanisms by which temporal information is utilized by the central nervous system in movement planning and execution and how such sensorimotor transformations are disrupted with aging and in Parkinson's Disease. Auditory, visual and combined auditory-visual stimuli will be used as external timing cues during the generation of rhythmic, sequential arm movements. Motor tasks will include unilateral and bilateral movements in which task complexity will be modified by manipulation of spatio-temporal parameters. By examining a broad repertoire of movements, it will be possible to delineate those motor tasks most sensitive to sensory cueing. Decreased variability in movement duration and end-point position as well as task-specific improvement in speed and inter limb coordination will serve as functional outcome measures of sensory facilitation in the production of sequential motor tasks. Enhanced control of movement dynamics will be assessed by examining changes in the relationship between joint angular rotation, movement trajectories and timing of opposing muscle groups. A three dimensional motion analysis system and surface electromyography will be used to obtain kinematic and muscle activity data. All data will be collected on-line and interactive computer software will be used for off-line quantification. These studies represent a unique cross-disciplinary approach to movement rehabilitation by combining expertise in motor physiology, physical medicine and neurology and will be the first in-depth, quantitative evaluation of sensory enhanced motor performance in elderly subjects and Parkinson's Disease.